This invention is generally directed to certain phthalocyanines such as metallophthalocyanines and, more specifically, the present invention is directed to alkoxy-bridged metallophthalocyanine dimers, processes thereof, and photoconductive imaging members thereof. In embodiments, the present invention is directed to novel metallophthalocyanine dimers, such as alkoxy-bridged metallophthalocyanine dimers of a trivalent metal of the following Formula 1 wherein the substituents are as illustrated herein ##STR2## that is M is a metal, and R is an alkyl group or an alkyl ether.
Also in embodiments, the present invention is directed to specific alkoxy-bridged metallophthalocyanine dimers, including alkoxy-bridged gallium phthalocyanine dimers. The alkoxy-bridged metallophthalocyanine dimers of the present invention can be obtained by the reaction of ortho-phthalodinitrile or 1,3-diiminoisoindoline with complexes of trivalent metals, such as the alkoxides, acetates or acetylacetonates, in the presence of a dialcohol (diol).
The resulting alkoxy-bridged metallophthalocyanine dimers, such as alkoxy-bridged galliumphthalocyanine dimers can be selected for utilization in layered photoconductive imaging members, including those that possess infrared photosensitivity, for example from about 700 to about 850 nanometers, and wherein the dimer is selected as the photogenerating pigment. The formed dimer can be selected as the photogenerating pigment or the dimer can be converted to the corresponding hydroxy metallophthalocyanine which phthalocyanines may be selected as the photogenerating pigment.
In embodiments, trivalent metal alkoxides can be obtained from the reaction of the corresponding trivalent metal halide with an alkali metal salt of an alcohol (alkali metal alkoxide), and the alkali metal halide byproduct formed may be removed by filtration. In embodiments, the trivalent metal alkoxides can alternatively be obtained from the reaction of the corresponding trivalent metal halide with an alcohol in the presence of a base such as ammonia, and the ammonium halide byproduct formed may be removed by filtration. Once formed, the trivalent metal alkoxide can be separated from the halide byproduct, or it may be utilized in situ in the subsequent reaction with a diol to form the alkoxy-bridged metallophthalocyanine dimer. In embodiments, the trivalent metal alkoxide can be prepared by reacting a gallium halide, especially the chloride, and an alkali metal alkoxide, and thereafter reacting the resulting gallium alkoxide with, for example, phthalodinitrile or 1,3-diiminoisoindoline in the presence of a diol, plus an optional organic solvent like N-methylpyrrolidone, a halonaphthalene like 1-chloronaphthalene, quinoline, and the like to form the alkoxy-bridged galliumphthalocyanine dimer. Further, in embodiments the process of the present invention comprises the reaction of a trivalent metal halide like gallium trichloride with an aliphatic alcohol like butanol in the presence of a base, such as ammonia, and subsequently reacting the resulting gallium butoxide with, for example, ortho-phthalodinitrile or 1,3-diiminoisoindoline in the presence of a diol, and an optional organic solvent to form the alkoxy-bridged galliumphthalocyanine dimer. The aforementioned and other processes for the preparation of dimers and trivalent metal alkoxide and imaging members thereof are illustrated in copending patent applications U.S. Ser. No. 233,834, U.S. Ser. No. 233,832, U.S. Serial No. 233,195, the disclosures of which are totally incorporated herein by reference.
The alkoxy-bridged metallophthalocyanine dimers, or the corresponding hydroxy metal phthalocyanines obtained from the hydrolysis of the dimer, such as hydroxy gallium phthalocyanine Type V can be selected as organic photogenerator pigments in layered photoresponsive imaging members with charge transport layers, especially hole transport layers containing hole transport molecules such as known tertiary aryl amines. The aforementioned photoresponsive, or photoconductive imaging members can be negatively charged when the photogenerating layer is situated between the hole transport layer and the substrate, or positively charged When the hole transport layer is situated between the photogenerating layer and the supporting substrate. The layered photoconductive imaging members can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic imaging and printing processes wherein negatively charged or positively charged images are rendered visible using toner compositions of appropriate charge polarity. In general, the imaging members are sensitive in the wavelength region of from about 550 to about 900 nanometers, and in particular, from about 700 to about 850 nanometers, thus diode lasers can be selected as the light source.
In embodiments, the alkoxy-bridged metallophthalocyanine dimers, such as alkoxy-bridged galliumphthalocyanine dimers of the present invention, can be selected as photogenerator pigments in photoresponsive imaging members. These photoresponsive imaging members may be layered photoconductive imaging members, and may contain separate charge transport layers, especially hole transport layers containing hole transport molecules. The imaging members containing alkoxy-bridged metallophthalocyanine dimers possess infrared photosensitivity and are sensitive in the wavelength regions of from about 650 to about 850 nanometers, therefore, diode lasers can be selected as the light source. The layered photoconductive imaging members can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic imaging and printing processes wherein negatively charged or positively charged images are rendered visible using toner compositions of appropriate charge polarity. The alkoxy-bridged metallophthalocyanine dimers can also be selected as precursors for the preparation of other phthalocyanines, such as hydroxy metallophthalocyanines, which phthalocyanines may be selected as a photogenerating pigment in photoresponsive imaging members.
The present invention is also directed to efficient synthetic methods for obtaining alkoxy-bridged metallophthalocyanine dimers by utilizing trivalent metal alkoxides obtained from metal halides as indicated herein. Alkoxy-bridged metallophthalocyanine dimers can be obtained by the reaction of ortho-phthalodinitrile or 1,3-diiminoisoindoline with a trivalent metal alkoxide in the presence of a diol. During the aforementioned reaction, the diol, which can also act as a solvent for the reaction, is chemically incorporated into the phthalocyanine product with the formation of an alkoxy-bridged metallophthalocyanine dimer of the formula C.sub.32 H.sub.16 N.sub.8 MOROMN.sub.8 H.sub.16 C.sub.32 as illustrated herein, wherein M is a trivalent metal, and the alkoxy bridge (O-R-O) contains the diol moiety (R). The alkoxy-bridged metallophthalocyanine dimers can also be obtained by the reaction of ortho-phthalodinitrile or 1,3-diiminoisoindoline with other complexes of trivalent metals, such as the acetates and acetylacetonates, in the presence of a diol. Alternatively, the alkoxy-bridged metallophthalocyanine dimers can be prepared by the reaction of hydroxy metallophthalocyanines of a trivalent metal with a diol, in the presence of excess diol or another solvent.
In embodiments the present invention is also directed to an efficient and economical process for the preparation of alkoxy-bridged metallophthalocyanine dimers by the in situ formation of trivalent metal alkoxides from metal halides. The metal halides are about one-tenth the cost and readily available from various sources such as APL Engineered Material, Urbana, Ill. and Gallard Schlesinger Industries, Carle Place, N.Y., which supply specific inorganic or organometallic chemicals on multi kilogram scale from stock supplies, compared to the corresponding trivalent metal alkoxides, acetates and acetylacetonates, which are usually special order produced on less than one kilogram scale. Thus, the alkoxy-bridged metallophthalocyanine dimers of the present invention can be prepared in efficient, economical and high yield, 70 to 85 percent, synthesis from metal halides:
Certain phthalocyanines, and especially metal phthalocyanines, can be selected as pigments and colorants in printing inks, paints, coatings, plastics, catalysts, chemical sensors, electrophotography, especially xerography wherein the phthalocyanines function as photogenerating pigments, laser sensitive materials for information storage systems, electrochromic display devices, and photobiology.
Specific metallophthalocyanines containing two phthalocyanine rings in the molecule have been described in the literature. In P.A. Barrett et al. in J. Chem Soc., 1717, 1936, there is illustrated (AlPc).sub.2 O, a .mu.-oxo bridged aluminum phthalocyanine of Formula 2. ##STR3##
The formation of a similar compound of trivalent Fe, (FePc).sub.2 O by aeration of FePc was described by C. Ercolani et al. in Inorg. Chem., 25, 3972, 1986.
Bis(phthalocyaninato)lanthanide(III) complexes, also described as lanthanide diphthalocyanines [L(Pc).sub.2 ] were reported by I.S. Kirin et al. in Russ. J. Phys. Chem (Engl Transl), 41,251, 1967. The lutetium phthalocyanine dimer was well studied according to the literature, for example for its electrochromic properties. Phthalocyanines Properties and Applications, 1989, VCH Publishers, Inc., edited by C.C. Leznoff and A.B.P. Lever, describes a series of these materials with the corresponding original references thereto.
Diphthalocyanines of tetravalent metals, such as stanium, Sn(Pc).sub.2, and zirconium, Zr(Pc).sub.2, of the structure shown in Formula 3, have been synthesized and described by W.R. Bennet et al. in Inorg Chem. 12, 930, 1973 and J. Silver et al. in Polyhedron, 8, 1631, 1989. ##STR4##
In the aforementioned documents there is no disclosure, it is believed, of the alkoxy-bridged metallophthalocyanine dimers of the present invention, such as alkoxy-bridged gallium phthalocyanine dimers, and their use as photogenerating pigments, as precursors, for example, in the preparation of hydroxygallium Type V phthalocyanines, or for the preparation of other phthalocyanine compounds, such as hydroxymetallo phthalocyanines, as illustrated in copending application U.S. Ser. No. 233,834, the disclosure of which is totally incorporated herein by reference.
Many halometallo- and hydroxymetallo phthalocyanines of trivalent metals, such as Al, Ga and In, are described in the literature, for example in The Phthalocyanines, vols. I and II, F.H. Moser and A.L. Thomas, CRC Press Inc., 1983 and by J.P. Linsky et al. in Inorg. Chem. 19, 3131, 1980.
In Bull. Soc. Chim. Fr., 23 (1962), there is illustrated the preparation of chlorogallium phthalocyanine by reaction of o-cyanobenzamide with gallium chloride in the absence of solvent, and hydroxygallium phthalocyanine by dissolution of chlorogallium phthalocyanine in concentrated sulfuric acid, followed by reprecipitation in diluted aqueous ammonia. Further, there are illustrated in JPLO 1-221459 (Toyo Ink Manufacturing) processes for preparing chlorogallium phthalocyanines and hydroxygallium phthalocyanines, as well as photoreceptors for use in electrophotography. A number of hydroxygallium phthalocyanine polymorphs and processes for the preparation thereof are described in JPLO 5-263007, the disclosure of which is totally incorporated herein by reference.
Further, hydroxygallium phthalocyanine is generally obtained by the hydrolysis of chlorogallium phthalocyanine. Ring chlorination often occurs in the preparation of chlorogallium phthalocyanine because gallium chloride is used at high temperature in the phthalocyanine synthesis, and this can effect the purity of the final product. This chlorine incorporation can result in detrimental properties when the phthalocyanine is used in special high purity applications such as electrophotography. This problem can be avoided by using an alkoxy-bridged gallium phthalocyanine dimer as the precursor. The alkoxy-bridged gallium phthalocyanine dimer can be hydrolyzed to hydroxygallium phthalocyanine by standard methods, such as by treatment with sulfuric acid, using a procedure similar to that described for the hydrolysis of chlorogallium phthalocyanine in Bull. Soc. Chim. Fr., 23 (1962). The hydroxygallium phthalocyanine can then be converted to the photosensitive Type V polymorph as described in copending application U.S. Ser. No. 233,834. By using an alkoxy-bridged gallium phthalocyanine dimer precursor in the preparation of Type V hydroxygallium phthalocyanine, any negative effects of residual chlorine, or ring chlorination, such as higher dark decay and higher cycle down, are avoided or minimized.
The alkoxy-bridged metallophthalocyanine dimers, shown by Formula 1 and described herein, are considered novel phthalocyanine dimers, or diphthalocyanines, which have an alkoxy bridge (O-R-O-) linking the two metal atoms of the metallophthalocyanine rings. The structure between the two oxygen molecules of the bridge is determined by the diol used in the synthesis. The trivalent metal in the phthalocyanine dimer structure can be selected from a number of components, such as aluminum, gallium or indium, or trivalent transitional metals, such as Mn(III), Fe(III), Co(III), Ni(III), Cr(III), and the like. In embodiments, this invention relates to alkoxy-bridged gallium phthalocyanine dimers as representatives of the new class of alkoxy-bridged metallophthalocyanine dimers.
Further, there is illustrated in JPLO 221459 a photoreceptor for use in electrophotography comprising a charge generation material and charge transport material on a conductive substrate, and wherein the charge generation material comprises one or a mixture of two or more of gallium phthalocyanine compounds which evidence the following intense diffraction peaks at Bragg angles (2 theta+/-0.2.degree.) in the X-ray diffraction spectrum,
1-6.7, 15.2, 20.5, 27.0 PA1 2-6.7, 13.7, 16.3, 20.9, 26.3 PA1 3-7.5, 9.5, 11.0, 13.5, 19.1, 20.3, 21.8, 25.8, 27.1,33.0.
In Konica Japanese 64-17066/89, there is disclosed, for example, the use of a new crystal modification of titanyl phthalocyanine (TiOPc) prepared from alpha-type TiOPc (Type II) by milling it in a sand mill with salt and polyethylene glycol. This publication also discloses that this new polymorph differs from alpha-type pigment in its light absorption and shows a maximum absorbance at 817 nanometers while the alpha-type exhibits a maximum at 830 nanometers. The Konica publication also discloses the use of this new form of TiOPc in a layered electrophotographic device having high photosensitivity at exposure radiation of 780 nanometers. Further, this new polymorph of TiOPc is also described in U.S. Pat. No. 4,898,799 and in a paper presented at the Annual Conference of Japan Hardcopy in Jul. 1989. In this paper, this same new polymorph is referred to as Type Y, and reference is also made to Types I, II, and III as A, B, and C, respectively. Also, in U.S. Serial No. 169,486 (D/93427), the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of hydroxygallium phthalocyanine Type V, essentially free of chlorine, whereby a pigment precursor Type I chlorogallium phthalocyanine is prepared by reaction of gallium chloride in a solvent, such as N-methylpyrrolidone, present in an amount of from about 10 parts to about 100 parts, and preferably about 19 parts, with 1,3-diiminoisoindoline (DI.sup.3) in an amount of from about 1 part to about 10 parts, and preferably about 4 parts DI.sup.3 for each part of gallium chloride that is reacted; hydrolyzing said pigment precursor chlorogallium phthalocyanine Type I by standard methods, for example acid pasting, whereby the pigment precursor is dissolved in concentrated sulfuric acid and then reprecipitated in a solvent, such as water, or a dilute ammonia solution, for example from about 10 to about 15 percent; and subsequently treating the resulting hydrolyzed pigment hydroxygallium phthalocyanine Type I with a solvent, such as N,N-dimethylformamide, present in an amount of from about 1 volume part to about 50 volume parts and preferably about 15 volume parts for each weight part of pigment hydroxygallium phthalocyanine that is used by, for example, ball milling said Type I hydroxygallium phthalocyanine pigment in the presence of spherical glass beads, approximately 1 millimeter to 5 millimeters in diameter, at room temperature, about 25 degrees, for a period of from about 12 hours to about 1 week, and preferably about 24 hours such that there is obtained a hydroxygallium phthalocyanine Type V, contains very low levels of residual chlorine of from about 0.001 percent to about 0.1 percent, and in an embodiment about 0.03 percent of the weight of the Type V hydroxygallium pigment, as determined by elemental analysis.
Further, in U.S. Pat. No. 5,407,766, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of hydroxygallium phthalocyanine Type V, which comprises formation of a precursor of gallium phthalocyanine, prepared by reaction of 1,3-diiminoisoindoline with gallium acetylacetonate in a suitable solvent; hydrolyzing the precursor by dissolving in a strong acid and then reprecipitating the dissolved pigment in aqueous ammonia, thereby forming Type I hydroxygallium phthalocyanine; and admixing the Type I hydroxygallium phthalocyanine with a polar aprotic organic solvent; and more specifically a process for the preparation of Type V hydroxy gallium phthalocyanine, which comprises preparing a precursor gallium phthalocyanine by the reaction of 1,3-diiminoisoindoline with gallium acetylacetonate in a suitable solvent; filtering and thereafter washing the pigment precursor gallium phthalocyanine with hot N,N-dimethylformamide, followed by washing with an organic solvent, such as methanol or acetone; hydrolyzing said precursor by dissolving in a strong acid and then reprecipitating the dissolved pigment in aqueous ammonia, thereby forming Type I hydroxygallium phthalocyanine; and admixing the Type I with the organic solvent N,N-dimethylformamide.
In copending patent applications filed concurrently herewith, there is illustrated in U.S. Ser. No. 233,834 a process for the preparation of Type V hydroxygallium phthalocyanine which comprises the in situ formation of an alkoxy-bridged gallium phthalocyanine dimer, hydrolyzing said alkoxy-bridged gallium phthalocyanine dimer to hydroxygallium phthalocyanine, and subsequently converting the hydroxygallium phthalocyanine product obtained to Type V hydroxygallium phthalocyanine; and a process for the preparation of Type V hydroxygallium phthalocyanine which comprises the formation of an alkoxy-bridged gallium phthalocyanine dimer by the reaction of an organic gallium complex with ortho-phthalodinitrile or 1,3-diiminoisoindoline and a diol; hydrolyzing the resulting alkoxy-bridged gallium phthalocyanine dimer to hydroxygallium phthalocyanine, and subsequently converting the hydroxygallium phthalocyanine product obtained to Type V hydroxygallium phthalocyanine; U.S. Ser. No. 233,832 a photoconductive imaging member comprised of an alkoxy-bridged metallophthalocyanine dimer as a charge generator material, wherein the dimer is of the formula C.sub.32 H.sub.16 N.sub.8 MOROMN.sub.8 H.sub.16 C.sub.32 wherein M is a trivalent metal, and R is an alkyl group or an alkyl ether group ##STR5## and U.S. Ser. No. 233,195 a process for the preparation of alkoxy-bridged metallophthalocyanine dimers by the reaction of a trivalent metal compound with ortho-phthalodinitrile or 1,3-diiminoisoindoline in the presence of a diol.
The disclosures of all of the aforementioned publications, laid open applications, copending applications and patents are totally incorporated herein by reference.